The present invention relates to a position measuring system, a position measuring method, and a position measuring program for preparing positional data with an image of a predetermined measurement area.
A three-dimensional measuring system, i.e. a so-called laser scanner, has been known in the past. According to this three-dimensional measuring system, a pulsed beam for measurement is projected to an object to be measured for scanning, and a distance is measured according to a light reflected from the object to be measured. Three-dimensional measurement of the object to be measured is conducted according to a value of the measured distance and a value of a projection angle of the light, and position data is obtained. In this type of three-dimensional measuring system, three-dimensional point group data is obtained by calculating based on the measured distance value and the projection angle of the light. A type of measuring system is known, by which image data of the object to be measured is also obtained at the same time to acquire three-dimensional data with an image by synthesizing the image data with the point group data.
On the other hand, in this type of measuring system, the object to be measured is a three-dimensional object, and it is unavoidable that there is an area, which cannot be measured by the measurement from a single point. For this reason, it has been performed that the measurement with no defects can be attained by measuring point group data on the object to be measured from a plurality of points in different directions and by synthesizing a plurality of point group data thus measured on the same coordinates. In this respect, in the method for synthesizing the point group data in the prior art, a target for the purpose of synthesis is installed on the object to be measured, and by measuring this target with high accuracy, coordinate transformation is performed based on the result of measurement on the target. Or, another method is known, in which three or more points common to two point group data are set up, and coordinate transformation is performed. After approximate position alignment, the distance between two point group data is turned to the minimum.
According to the prior art, however, a target must be installed on the object to be measured, and this means that complicated procedure is required for the installation of the target. Also, it is difficult to install the target when the object to be measured is located at high position. In the case where the target is not installed, synthesis must be made by merely depending on the shape of the point group data, and this means that the object to be measured must have special characteristics such as irregular surfaces or the like. There has been such problems that the characteristics such as irregular surfaces or the like may exert detrimental influence on the accuracy of the synthesis.